The correct option is 2 and 3 only.
Explanation
Water vapour is a highly variable gas in the atmosphere, ranging from nearly 0 % to 4 % by volume. Its concentration is primarily determined by temperature and the availability of moisture sources.
Statement-wise Analysis:
- Statement 1 is Incorrect: In warm and wet tropical regions, the air temperature is high, allowing it to hold a significant amount of moisture. In these areas, water vapour may account for up to 4 % of the air by volume, not less than 0.1 %.
- Statement 2 is Correct: In dry and cold environments, such as deserts and polar regions, the air's capacity to hold moisture is significantly reduced. Consequently, the water vapour content in these areas is very low, often constituting less than one % of the air by volume.
- Statement 3 is Correct: The distribution of water vapour exhibits a distinct latitudinal pattern. It generally decreases from the equator towards the poles because the moisture-holding capacity of air diminishes as temperatures drop at higher latitudes.
Key Takeaway:
Water vapour is the most variable atmospheric constituent (0-4% by volume), with its concentration being highest in warm, wet tropics and lowest in cold, dry polar or desert regions.